Field of the Invention
The present invention relates to a technique for collecting ink mist in an inkjet printing.
Description of the Related Art
In printing of an inkjet method, ink mist is generated in association with an ink ejection operation of a print head. In some cases the mist adheres to a conveyance passage of a sheet to contaminate the sheet to be conveyed thereon or adheres to various sensors to cause erroneous detections. For addressing the above problems, Japanese Patent Laid-Open No. H02-179761(1990) describes a technique that a suction fan is used to suction and collect the mist.
In Japanese Patent Laid-Open No. H02-179761(1990),an intensity of the suction is set to the extent of not affecting a landing position of ink ejected from a print head, that is, a print quality at the printing time. As the suction gets stronger, collection efficiency of the mist improves, but in consideration of the print quality degradation, the suction intensity is suppressed on purpose.
In the inkjet printing, a preliminary ejection is performed for maintenance of the print head in addition to the print operation. Since inks are ejected from all the nozzles in the preliminary ejection, more mist tends to be generated than at the printing time. However, in Japanese Patent Laid-Open No. H02-179761(1990), no consideration is given on how to suction mist generated at the time other than at the print operation.